Carbon stock and density of soils under chir pine ( Sargent) forests of Solan forest division, Himachal Pradesh Pinus roxburghii Shipra Shah , D.P. Sharma , Nazir A. Pala , PriyankaTripathi andAyoub Dar 1 1 2 1 3 1 2 3 2 Dr. Y. S. Parmar University of Horticulture and Forestry Nauni, Solan; Faculty ofAgriculture, Himgiri Zee University, Sherpur, Chakratra Road, Dehradun; CSWCRTI, 218, Kaulagarh Road, Dehradun-248195, Uttarakhand E-mail : nazirpaul@gmail.com ARTICLE INFO Article history : Received : , 201 Revised : Accepted : September, 2013 Februry 3 August, 2013 Key words : Depth, Organic carbon, Pine forest, Range, Soil carbon, Solan ABSTRACT Soil carbon status of chir pine forests was studied in the chir pine working circle of two forest ranges (Solan and Dharampur) of Solan Forest Division, in Himachal Pradesh, at an altitudinal gradient from 600-2260 m amsl. A total of 33 forest compartments were selected for the study. The soil samples were collected from humus layer, 0-20 cm, 20-40 cm, 40-100 cm soil depth. The results showed that the soil pH increased while electrical conductivity decreased with increasing depth. The soil organic carbon (%) decreased with increasing soil depth, while soil bulk density showed the reverse trend with increasing soil depth. The soil carbon stock ranged from 18.87 to 317.31 t in the humus layer, from 127.87 to 2069.10 t at a depth of 0 to 20 cm, from 118.37 to 1675.80 t at 20 to 40 cm depth and from 207.35 to 3441.20 t at 40 to 100 cm soil depth. The soil carbon density ranged from 6.73 to 9.62 t ha in the humus layer, from 33.73 to 55.80 t ha at a depth of 0 to 20 cm, from 30.52 to 50.46 t ha at 20 to 40 cm depth and from 81.84 to 99.83 t ha at 40 to 100 cm soil depth. -1 -1 -1 -1 1. INTRODUCTION Soil carbon measurement is the focus of current and future international negotiations and treaties related to global change. However, more efficient methods of measuring soil carbon are required to support better estimates of terrestrial carbon inventories and inventories and fluxes for efficient management (NRC, 1999). Improved terrestrial carbon inventories may require many more measurements than can be delivered economically using current technologies and approaches. Soil organic carbon (SOC) is the largest carbon reservoir in many terrestrial ecosystems including grasslands, savannas, boreal forests, tundra, some temperate forests, and cultivated systems, comprising as much as 98% of ecosystem carbon stocks in some systems (Schlesinger, 1977). It has been estimated that SOC sequestration has the potential to mitigate 5-14% of total annual greenhouse gas emissions for the next 50-100 years (Chan ., 2008). A substantial portion of carbon fixed by vegetation is transferred to the soil annually (Raich and Nadelhoffer, 1989), a portion of which is refractory material with long turnover times, the rest decomposes relatively rapidly and is returned to the atmosphere as CO (Falloon and Smith, 2000). et al 2 Estimates of total global soil organic carbon are converging on about 1500 PgC in top 1 m soil (Adams ., 1990; Eswaran ., 1993). This is two times the amount of 750 PgC in atmosphere as CO ; while estimates referring to top 2 m suggest that another 900 PgC could occur at a depth of 1-2 m (Batjes, 1996). IPCC (2000) estimated the total soil carbon pool in top 1 m as 2011 PgC. Lal (1999) gave a conservative estimate of soil carbon pool as 2300 PgC, which is about 4.1 times the biotic pool, and about three times the atmospheric carbon pool. Globally carbon stocks in the soil exceed carbon stocks in vegetation by a factor of about 5. The ratio ranges from 1:1 in tropical forests to 5:1 in boreal forest and much larger factors in grasslands and wetlands (IPCC, 2000). Forest ecosystems merit consideration in this context of climate change because they can act as sources as well as sinks of CO , the most abundant greenhouse gas (Haripriya, 2002). Expanding carbon storage in forests has been identified as a potential measure to mitigate climate change (FAO, 2001; DeFries ., 2000). About two-thirds of terrestrial C, exclusive of that sequestered in rocks and sediments, is sequestered in the standing forests, forest understorey plants, leaf and forest debris, and in forest soils et al et al et al 2 2 E st d. 1 9 7 2 Vol. , No. , pp , 201 41 3 279-286 3 Indian Journal of Soil Conservation Online URL:http://indianjournals.com/ijor.aspx?target=ijor:ijsc&type=home